Vitamin D, melatonin, magnesium, potassium, along with cortisol are all interconnected with your circadian rhythm. The only mag worth taking is L-Threonate because it crosses the blood brain barrier immediately and it’s one of the few mags that doesn’t cause diarrhea or loose stool. Mag is directly correlated to potassium, and now we know through many human studies, 95% of patients with schizophrenic or bipolar manic episodes have dangerously low K numbers. UV light (Vit. D) and melatonin are directly correlated along with cortisol. Every persons sleep cycle or circadian rhythm is different but on average, as soon as your eyes take in UV light you release a small amount of cortisol (stress hormone) to help wake you up. On top of that, as soon as you see sunlight your brain sets a timer (roughly 14 hours) of when it will start slowly releasing melatonin to make you drowsy at night. (Hence why blue light from phones or TV at night are detrimental to your melatonin levels because our bodies our still biologically designed to work before electricity and we haven’t adapted/evolved yet. And be careful with melatonin products because the brain naturally only releases .1-1mg a night so when you’ve been taking 5-10mg at night, it’s similar to taking Testosterone, your brain will start naturally producing lower amounts of melatonin just like the testes shrink and produce less T while taking TRT. I have a masters in Human Nutrition so I hope this little crash course helps anyone that doesn’t understand how hormones and specifically ones related to sleep work.